Formula One is, on the one hand, a magnificent waste of money and resources, but on the other, it’s a hot-bed of technological advances, which trickle down into the vehicles that we mere mortals drive. Even my VW Passat has paddles to change gear! But F1 doesn’t just benefit cars: its influence extends to loudspeakers as well, as the fins in the mouth of the vent of a PMC twenty5 series model were put there as a result of lessons learned on the track. Put fins or ‘strakes’ as they call them into an aerofoil and they allow air to flow more easily. That seems like a paradox, as how can putting something in the way of air improve the flow of that air? That comes down to turbulence; the fins reduce the turbulence at the point where the air escapes the vent. This does two things; it allows more of the energy coming from the back of the driver to be heard as sound, and critically means that the driver can have higher excursion and thus deliver higher sound pressure levels. It was PMC’s desire to give the twenty5 series greater sound pressure level/volume capabilities that led to the development of the Laminair vent as it has been dubbed, that and the need for a stiffer cone material of which more anon. The fact that it becomes more efficient, and can convert more energy into sound at low frequencies, is the icing on the cake.
The twenty5.26 is the largest model in the range and the only one with a midrange driver. It’s a proper three-way in fact, with similarities to the mighty Fact.12. It stands just over a metre tall before you add a pair of stainless steel plinth bars that are spaced from the cabinet with cork isolators. These extend the footprint of the fairly slim cabinet and add stability when combined with the rather nice custom made stainless spikes.
The cabinet itself has the same back-swept lean that PMC developed for the twenty series and would seem to have become a bit of a signature for the brand. It houses a 3.3m transmission line with twin Laminair vents at the front and a single pair of cable terminals on the back. The move away from bi-wirability is a controversial one, but has been practiced by certain successful brands for some time. It also minimises the distance between input and crossover and means that single-wirers like myself don’t need to use the bridging plates that undermine many bi-wirable designs. The terminals themselves are particularly nice custom made examples in rhodium-plated copper, they accept spade, banana, and bare wire connections.